From 1768c4597e70477af2d69f576f33400181a5f945 Mon Sep 17 00:00:00 2001
From: Christoph Stiller <c.stiller@live.de>
Date: Tue, 18 Jul 2023 13:36:37 +0100
Subject: [PATCH] [MCA] Document behaviour of ResourceRef

Differential Revision: https://reviews.llvm.org/D155347
---
 llvm/include/llvm/MCA/HWEventListener.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/llvm/include/llvm/MCA/HWEventListener.h b/llvm/include/llvm/MCA/HWEventListener.h
index 4a7d0df6b18a9..a24b90654e2f1 100644
--- a/llvm/include/llvm/MCA/HWEventListener.h
+++ b/llvm/include/llvm/MCA/HWEventListener.h
@@ -59,7 +59,10 @@ class HWInstructionEvent {
   const InstRef &IR;
 };
 
+// ResourceRef::first is the index of the associated Resource.
+// ResourceRef::second is a bitmask of the referenced sub-unit of the resource.
 using ResourceRef = std::pair<uint64_t, uint64_t>;
+
 using ResourceUse = std::pair<ResourceRef, ResourceCycles>;
 
 class HWInstructionIssuedEvent : public HWInstructionEvent {